Switch mechanism for talking-motion-picture exciting lamps



July 1 1930," 1L. DE FOREST 1 1,769,909 SWITCH MECHANISM FOR TALKING MIOITION'PIC'IIURE EXCITING LAMPs Filed Aug. 24, 1929 fi/m Car 4 sound F? cord @51 5 Carr in 03d Rczr ds 4 N f g (Q Z-Jvwemtoz T 1 ea DefBresf hatente duty 1, E93

LEEDE FOREST, OF NEW YORK, N. 'Y., ASSIGNOR TO GENERAL TALKING PICTURES CUE- ?OBATION, OF NEW YORK, N. Y.,

A CORPORATION OF DELAWARE ISM FOB TALKING-MOTION-PICTURE EXCITING LB Application filed August 24, 1929. Serial No. 388,135.

This invention relates to improvements in talking motion picture equipment as used in theatres where two projection machines each carrying an attachment for reproducing sound from film are employed.

One of the objects of this invention is the provision of an automatic switching arrangement by means of which the exciting lamp of the projection machines in use may be deenergized and the exciting lamp of the projection machine about to be used may be energized all at the instant when the sound amplifying device has been turned down to the point of minimum amplification.

Another object of this invention is the association with the so called fader used in connection with the sound amplifier of talking motion picture apparatus of acontrolling switch for disconnecting one exciting lamp and connecting another exciting lamp at the proper time.

A still further object of this invention 1s the provision of apparatus of this nature in which a change-over from one sound reproducing device to another may be made at a time when no audible sound will be produced in the loud speakers connected to the sound reproducers.

These and other objects as will appear from the following disclosure are attained by means of the construction comprising this invention.

lhis invention resides substantially in the combination, construction, arrangement, relative location of parts and circuital connections, all as will be described in greater detail hereinafter.

Referring to the drawings- Figure 1 is a diagrammatic illustration showing the association of the fader, the change-over, the switch, the two exciting lamps, and the current source therefor:

Flgs. 2 and 3 are front and side elevational views ofone suitable form of change-over switch.

in talking motion picture equipment as used in theatres where two projection machines each cargingan attachment for reproducing soun from photogra hic sound records on a e e p y d it i .esi b z ta have some form of change-over device so that in changing from one sound reproducing attachment to the other no audible sound will be produced in the loudspeakers by reason of the change in circuit connections. It is the practice at the present time to provide two projection machines with sound reproducing attachments for reproducing the sounds on pictures first through one machine and at the end of the film therein effect a quick changeso over to the succeeding film in the other projection machine. With this arrangement a picture comprising the several reels of filmaving sound records thereon may be reproduced in succession without causing any interruption in the continuous projection of the picture and the continuous reproduction of the sound and without causing any undesired noises in the loud speakers at the time of change-over. It is the custom to employ at Ft the instant of throw-over from one machine to the other a device called a fader for gradually cutting down the amount of amphfica tion of the sounds from the sound reproducing attachment on the first machine and im- 76 mediately bringing up the volume of sound from the sound reproducing attachment on the second projection machine. Such a so called fader device is now well known in the art and alone forms no art of this invenea tion. It consists merely 0 adjustable resistances connected in the vacuum tube amplifier system so that the volume of sound output may be controlled and particularly at the time when a chan e-over from one reel to at another is being e ected.

The fader is shown diagrammatically in Figure 1 as comprising a panel 1 having two sets of contacts 2 and 3 mounted in a circle thereon. Contacts 4 and 5 are dead while the other contacts are connected to resistances in a well known manner to give a step by step adjustment. The resistances connected to contacts 2 are connected in a well known mannor to the amplifier connected in the output of the light valve not disclosed. In a simllar manner the resistance connected to contacts 3 are connectedto the amplifier in the output circuit of the light valve for the other sound reproducing attachment. All this is ice known as well as the fact that thelight valves in each case are placed on the opposite sides of the films 23 and 25 from the lens systems 22 and 24 and in ali nment therewith.

Mounted on pane 1 is a control knob 6 which has the contact arm 7 thereon which contacts with the contact points 2 and 3. The end of the contact arm 7 is provided with a short rojection 8 of insulating material. Pivota ly mounted at 9 on the panel 1 is a switch arm 10 having a notch 11 in one end thereof., The switch arm 10 may assume either of two positions for engaging the contacts 12 and 13. The pivotal support'9 of the switch arm 10 is connected by wire 15 to one terminal of the current source 14. In present practice this current source is a storage battery. Contact 12 is connected by wire 17 to one terminal of the exciting lamp 19. Contact. 13 is connected by wire 16 to oneterminal of the exciting lamp 18. The other terminals of the exciting lamps 18 and 19 are connected together by wire 20 and by wire 21 to the other terminal of current source 14. The length of projection 8 is such that as the switch arm 7 approaches a downward vertical position it engages the notch 11 in switch arm 10 and swings it as for example in the drawing from the full line position to the dotted position. The light from the excitin lamps 18 and 19 is focused by means of the ens systems 22 and 24 respectively, upon the adjacent films 23 and 25 as is well known in-the art. v

In the operation of this device with the switch arm 7 on the uppermost contact 2 the amplifier for the light valve adjacent film 23 is at maximum setting. As the end of the film is ap roached the contact arm 7 is swung downwa ly in a clockwise direction by means of knob 6 to the lowermost contact 2 cansing a gradual reduction in the volume of sound output to the loud speaker connected to the amplifier. About the time the end of the film is reached projection 8 engages notch 11 and swings switch. arm 10 from contact 13 to contact 12. When switch arm 7 is on contact 5 the circuits to both exciting lamps are interrupted. As switch arm 7 passes on to the lowermost contact 3 and moves u wardly .to the highest contact the volume 0 output from the sound amplifier connected .to the light valve adjacent film 25 is gradually increased to the maximum value. Contact 4 is another dead contact which is engaged "by switch arm 7 when both exciting lamps are disengaged. By means of this arrangement other is efiected at the time when the control reaifiances for the amplifier are disconnected. Thislchange-over is made by gradually reducing the volume of sound output from' one sound reproducer and then gradually building it up on the other sound reproducer. .At one point in this change neither sound reproand of the current source.

lamps draw from 4 to 8 amperes which woul ducer is 0 rating since the exciting lamps are both isconnected. With this arrangement undesired sounds caused by the interruption and the making of the exciter lamp circuits in the loud s eakers is prevented. Another advantage 0 this arrangement is that it prolongs the life of the exciting lamps These exciting be a considerable drain on a storage battery if both lampsare lighted at the same time even for a s ort period. In addition the exciting lamps are burned at a ver high intensity and it is, therefore, highl esirable in order to prolong the life of the fi ms that each so lamp should be burned only when the rojection machine to which it is attached is in actual operation. Another advantage of this arrangement is that the operator in adjusting the fader which is always done during the period of chan e-over automaticall and without any volition on his part, eiiects a change-over from one excitin lamp to the other. A suitable switch for t is purpose is shown in Figs. 2 and 3. A portion of'the 00 panel is shown having the connecting post 9 thereon for pivotally supporting the switch arm. In this case a spring finger 28 is provided with a rejection 26 which has the notch 11 in the end engages two supporting pro ections 29 and 30, which also act as contacts electrically connected'together and finally connected to the common connection-15 of the current source 14. The spring fingers 10 and 28 are elecm trically connected together by the su ortin blocks 27. As before wire 17 will he con nected to contact 12 and wire 16 to contact 13 or vice versa. Of course, the switch arm when 1 in use never assumes the central position shown for it in Fig. 2 but is in either of its two operative positions at which time connection is made between contacts 13 and 28 or zpntacts 12 and 30 depending upon its posi- Ion.

ters Patent is:

1. In an apparatus of the type described, i I

two exciting switch at a predetermined time. the change-over from one exciting lamp to the k 2.- In an apparatus for reproducing sound from photographic records, the combination with a fader having a movable arm'there- 125 to sai switch including two exciting lamps '1 :20

thereof. The spring finger 28 95 What I seek to secure by United States Letr reproducing sound reno and a common current source whereby either one or the other of the exciting lamps is energized depending upon the position of said switch.

3. In an apparatus for producing sounds from photographic sound records, the combination comprising two variable resistances adapted to be connected-to the amplifiers of sound reproducing devices, means for varying said resistances, a single pole double throw switch, two exciting lamps for the sound records, a current source and connections including said current source, single pole double'throw switch and exciting lamps whereby one exciting lamp is energized and the other de-energized upon the movement of said means as it passes from one adjustable resistanceto the other.

4. In talking motion picture apparatus o the type described employing film strips having sound records thereon, the combination comprising a fades for controlling the amplifiers of two sound reproducing devices having a movable adjusting arm, a switch supported adjacent said arm so as to be thrown from one position to another upon the movement of said arm thereby, twoexciting lamps for the sound record strips and connections including said switches, and said exciting lamps including a common current source whereby upon" the movement of said switch one lamp is energized and the other is'deenergized. I

5. In an apparatus employing photographic sound films, the combination comprising two adjustable resistances for controlling two sound amplifiers, a switch arm for adjusting one or the other of said resistances, a switch mounted adjacent said arm and adapted to be engaged thereby at one point in the path of its movement, two exciting lamps for the sound films, a common current source, and connections between said exciting lamps, said common current source and said switch whereby upon engagement of said arm with said switch one lamp is energized and the other de-energized.

6. In an apparatus for use in connection with two motion picture rejection machines each carrying sound-onlmattachments for reproducing sound from photographic sound records including an exciting lamp in each attachment, a volume control device having a movable member, a switch mounted adjacent said movable member for engagement thereby, and connections'between said switch and said excitin lamps including a common current source w ereby u on engagement of said switch b said mova 1e member one of said excitin amps isenergized and the other de-energize I. Themethod of operating apparatus for reproducing sounds from photographic sound records, including exciting lamps which encased in succession, which comprises gradually reducing the volume of sound output from one sound reproducer, de-energizing the exciting lampfor that sound reproducer at the time when the volume of sound reproduced thereby is at a minimum and then energizing the other exciting lamp, and

ble resistances and acontrol arm therefor, I

of a switch adapted to be engaged and operated by the control arm during a portion of its movement when controlling one or-the other of said resistances, two exciting lamps focused on the sound films, a common current source and connections between said switch, exciting lamps and common current source whereby one exciting lamp is disconnected'from said common current source and the other connected thereto during the time when said control arm'engages said switch.

9. In an apparatus of the type described the combination comprising two exciting lamps for apparatus for reproducing sounds from photographic sound records, connections for said lamps including a common current source, a switch in said connections for de-energizingone exciting lamp and energizing the other exciting lamp upon movement thereof, and volume cont-r01 means adapted to be connected to the amplifiers of the sound reproducing apparatus including a movable control member adapted to operate said switch at the time when both amplifiers are adjusted for minimum sound volume output.

In testimony whereof I have hereunto set 

